Brake lights provides a visual indication to following vehicles of a deceleration of the leading vehicle, which is useful in helping to avoid vehicular accidents. A conventional brake light operation involves detection of braking by the vehicle driver (e.g., depression of the vehicle's brake pedal) and illumination of left and right brake lights on the rear of the vehicle, as well as that of a center high-mounted stop lamp (CHMSL).
It has been proposed to modify the illumination of the brake lights based on a sensed level of deceleration during a driver initiated braking event. WO 2009/049332 discloses a circuit that includes two accelerometers and a microcontroller used during driver braking to measure deceleration and tilt of a car and to determine if the car is undergoing emergency braking and, if so, to flash the brake lights rather than holding them constantly on during the braking. One disadvantage in such a system is that it is wholly dependent on driver braking to supply the operating power for the accelerometer circuit and cannot independently determine and warn of sudden decelerations. Thus, the system is not able to provide visual warning in the event of sudden decelerations by vehicle or external conditions other than braking or to continue to provide any such warning following an accident once the driver has released pressure on the brake pedal.